Physiological effects of hyperthermia: response of capillary blood flow and structure to local tumor heating.

Abstract

Specific capillary blood flow and small-vessel pathology in animal tumors (rhabdomyosarcoma BA-1112 cells) of WAG/Rij rats were examined following local tumor heating to 40-44.5.degree. C. Blood flow in tumors heated to 40-41.degree. C for 40 min was reduced initially by about 50%, but returned to near preheating values within 72 h, consistent with the histopathological observations indicating small-vessel dilation and temporary congestion. The application of hyperthermia [for cancer therapy] greater than 43.degree. C (for 40 min) resulted in the virtual elimination of capillary blood flow, consistent with pathological findings of widespread vessel rupture and hemorrhage in this temperature range.